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As many as 60,000 barrels of oil per day may be flowing from the blown-out wellhead in the Gulf of Mexico, according to the newest government estimates.

Basing their calculations partly on pressure readings from the wellhead and acoustic soundings, a team of federal and independent scientists said Tuesday the current daily well flow ranges from 35,000 to 60,000 barrels per day. The figures are the latest in a series of flow estimates that have steadily risen in recent weeks, but they may not be the last.

"As we continue to collect additional data and refine these estimates, it is important to realize that the numbers can change," said Energy Secretary Steven Chu. "In particular, the upper number is less certain, which is exactly why we have been planning for the worst-case scenario at every stage and why we are continuing to focus on responding to the upper end of the estimate, plus additional contingencies."

[Updated at 4:04 p.m.: Federal officials said they have greater confidence in the latest numbers than earlier ones because the new calculations are based on a greater variety of data. “This estimate brings together several scientific methodologies and the latest information from the sea floor, and represents a significant step forward in our effort to put a number on the oil that is escaping from BP’s well,” Chu said.

The new flow rates are based on high-resolution videos taken by underwater robots, acoustic soundings, new pressure readings from inside the recently installed containment cap and measurements of the volume of oil the cap is funneling to a production ship.

“This estimate ... is the most comprehensive estimate so far of how much oil is flowing one mile below the ocean’s surface,” Interior Secretary Ken Salazar said.

The higher flow rates are ratcheting up pressure on BP to quickly get enough tankers and equipment on site to capture the full amount.

On Monday, 15,420 barrels of oil were collected. The system BP currently has in place can capture up to 18,000 barrels a day. The company is adding additional capacity that will soon give it the ability to handle up to 28,000 barrels.

That will grow to about 50,000 barrels per day by the end of June and 60,000 to 80,000 barrels by mid-July, federal officials said.

The new estimates take into account any increase that occurred when a riser pipe attached to the well was sliced off early this month. Engineers had previously said the cut might push up the flow by as much as 20%. But Tuesday's release did not discuss the cut's effect. ]

In the early days of the spill, oil company BP and federal officials said the flow was 1,000 barrels per day, a figure that was ramped up to 5,000 after an environmental group challenged the figures. The scientific panel was formed, and it issued a preliminary estimate of 12,000 to 19,000 barrels per day. Last week, the same group upped its estimate to 20,000 to 40,000 barrels per day.

The day after the April 20 explosion of the Deepwater Horizon rig, the U.S. Coast Guard evaluated the "potential environmental threat" of a spill and concluded that, in addition to 700,000 gallons of diesel from the vessel, there was an "estimated potential of 8,000 barrels per day of crude oil, if the well were to completely blow out," according to Coast Guard documents released last week.

Two days later, Coast Guard logs included a new estimate that a full blowout could result in a spill of 64,000 to 110,000 barrels per day. (A barrel equals 42 gallons.)